For purposes of providing couplings in high pressure fluid circuits and the like, use has been made of wired fittings to lock parts together to prevent the decoupling thereof during operation. Such devices are known as lockwire fluid fittings and one such device is disclosed in U.S. Pat. No. 3,807,774 (Joseph W. Heath, Jr.) which issued Apr. 30, 1974. Therein are disclosed separate hydraulic fittings which are connected together by nuts at least one of which is engaged by a wire fitting in order to prevent separation of these components during operation. Such an arrangement is especially useful in aircraft wherein operation under conditions of high pressure and vibration sometimes result in the separation of parts to the detriment of satisfactory operation of the aircraft in which such a fitting is incorporated.
In an investigation of the novelty of the present invention, a number of patents have been found. These include U.S. Pat. Nos. 2,419,702 (F. A. Barnes); 2,420,778 (R. E. Herold); 3,053,357 (W. E. Stanger); 3,915,478 (Al et al); and 4,451,069 (Melone).
The Barnes U.S. Pat. No. 2,419,702 reveals the use of a coupling member to connect two members together. There is a provision for the striking out and peening over of a tongue from the metal of the coupling member. The tongue prevents unscrewing of one part from another. There is, however, no suggestion in this patent of a ramp providing for the taking of play out of and adding frictional torque to resist unlocking of a threaded engagement.
The Melone U.S. Pat. No. 4,451,069 is provided with cantilevers which bear bulbous tips adapted for being accommodated in an annular groove. A plurality of fingers are provided which are in cylindrical arrangement, the fingers being separated by respective slots. The bulbous tip of each finger is accommodated loosely in the associated annular groove.
The Herold U.S. Pat. No. 2,420,778 reveals the use of a coupling member to bring about engagement between axially displaceable parts. Therein, a tube is clamped between one part and an external sleeve to provide what looks like a ramp type engagement but which actually is unlike the ramp type engagement discussed hereinbelow.
The Al et al U.S. Pat. No. 3,915,478 includes an external sleeve for threadably engaging an interior sleeve such as to provide a coupling for a compression-type pipe. The coating terminates in a thread formation of composition tandemly juxtaposed and comprising an extension of metal thread thereon.
The Stanger U.S. Pat. No. 3,053,357 indicates a design consisting of a circular arrangement of cantilever like fingers with bulbous tips. The bulbous tips are accommodated loosely in an annular slot arrangement. There is, however, no threaded engagement which is enhanced by the engagement of a frustoconical ramp by a circular arrangement of fingers as discussed below.
None of the aforesaid patents discloses a coupling, suitable for operation in high pressure fluid circuits and the like, which provides for locking parts together without the use of wire connectors while additionally providing for improving the inter-engagement between threadably coupled components.